“正所谓入乡随俗”帮忙翻成英文，谢！

It is so-called when in Rome, do as the Romans.

这三种都可以，不需要拘泥与形式！

It is so-called "When in Rome, do as the Romans. "

It is namely "When in Rome, do as the Romans. "

This is what we said "When in Rome, do as the Romans. "

Just as the saying goes, do in Rome as the Romans do.

As is said,when in Rome, do as the Romans do.

参考：《中高级口译词汇短语巧记速记》 复旦大学外文学院 上海三联书店出版 第208页

So-called do as the Romans do while in Rome !